A flaw was found in grub2. A specially crafted JPEG file can cause the JPEG parser of grub2 to incorrectly check the bounds of its internal buffers, resulting in an out-of-bounds write. The possibility of overwriting sensitive information to bypass secure boot protections is not discarded.

A flaw was found in command/gpg. In some scenarios, hooks created by loaded modules are not removed when the related module is unloaded. This flaw allows an attacker to force grub2 to call the hooks once the module that registered it was unloaded, leading to a use-after-free vulnerability. If correctly exploited, this vulnerability may result in arbitrary code execution, eventually allowing the attacker to bypass secure boot protections.

When reading the language .mo file in grub_mofile_open(), grub2 fails to verify an integer overflow when allocating its internal buffer. A crafted .mo file may lead the buffer size calculation to overflow, leading to out-of-bound reads and writes. This flaw allows an attacker to leak sensitive data or overwrite critical data, possibly circumventing secure boot protections.

A flaw was found in grub2 where the grub_extcmd_dispatcher() function calls grub_arg_list_alloc() to allocate memory for the grub's argument list. However, it fails to check in case the memory allocation fails. Once the allocation fails, a NULL point will be processed by the parse_option() function, leading grub to crash or, in some rare scenarios, corrupt the IVT data.

grub2 allowed attackers with access to the grub shell to access files on the encrypted disks.

The GRUB2's shim_lock verifier allows non-kernel files to be loaded on shim-powered secure boot systems. Allowing such files to be loaded may lead to unverified code and modules to be loaded in GRUB2 breaking the secure boot trust-chain.

There's a use-after-free vulnerability in grub_cmd_chainloader() function; The chainloader command is used to boot up operating systems that doesn't support multiboot and do not have direct support from GRUB2. When executing chainloader more than once a use-after-free vulnerability is triggered. If an attacker can control the GRUB2's memory allocation pattern sensitive data may be exposed and arbitrary code execution can be achieved.

Out-of-bounds write when handling split HTTP headers; When handling split HTTP headers, GRUB2 HTTP code accidentally moves its internal data buffer point by one position. This can lead to a out-of-bound write further when parsing the HTTP request, writing a NULL byte past the buffer. It's conceivable that an attacker controlled set of packets can lead to corruption of the GRUB2's internal memory metadata.

Integer underflow in grub_net_recv_ip4_packets; A malicious crafted IP packet can lead to an integer underflow in grub_net_recv_ip4_packets() function on rsm->total_len value. Under certain circumstances the total_len value may end up wrapping around to a small integer number which will be used in memory allocation. If the attack succeeds in such way, subsequent operations can write past the end of the buffer.

GRUB2 does not call the module fini functions on exit, leading to Debian/Ubuntu's peimage GRUB2 module leaving UEFI system table hooks after exit. This lead to a use-after-free condition, and could possibly lead to secure boot bypass.